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Full text of "The Cambridge Natural History"

xiv                  ANCIENT   CARNIVORES----CREODONTA               455

incommoded by the direct rays of the sun, to the effects of
which they are very susceptible. The Elephant Seal is mild
and inoffensive, unless enraged, and, of course, during the
breeding season.

This entirely extinct group of Mammalia may be thus character-
ised :—Small to large carnivorous mammals, with skull on the
whole like that of the Carnivora and with trenchant teeth ; digits
with unguiculate phalanges; tail long ; extremities usually with
five, sometimes "with four digits. In the carpus a centrale is
present, and the scaphoid and lunar are separate. Interlocking
of posterior dorsal and lumbar zygapophyses very perfect. Brain
small but convoluted.
This group, which corresponds with the CARNIVORA PEIMI-
GENIA of Mr. Lydekker, is not easy to separate absolutely from the
existing and more especially from some of the extinct members
of the CARNIVORA VERA. They also come exceedingly near the
Condylarthra, the presumed ancestors of the Ungulata, and like
them begin in the earliest Tertiary deposits. Their likeness to
the carnivorous Marsupials has also been insisted upon; but it
would seem that the succession of teeth in the Creodonta is
typically Eutherian.
The characteristics of the group may be exemplified by an
account of the genus Hyaejiodon^ after which some of the more
important deviations in structure shown by other genera will be
referred to.
Hyaenodon is both American and European, and ranges
through the Eocene and the Upper Miocene, It is a much-
specialised Creodont, and therefore exhibits well the distinctive
characters of the group. About a dozen species have been
described. One of the best-known is the American If. cruentus,
and the following description refers to it. The back part
of the skull is low and broad, and is compared by Professor
Scott (who has described this and other species) as being
" somewhat like that of an opossum."1 The whole skull is
1 «7imr™. Ac. Sri. Philadelphia,, ix. 1886, p. 175.